GaN power integrated circuits (IC) have the potential of dramatically reducing the size and weight of power electronic systems, thereby substantially reducing the cost of power electronic devices. P-channel GaN-transistor is a critical component for making GaN power ICs. Such power electronic systems are widely needed in electric/hybrid vehicles, more-electric aircrafts, as well as many consumer electronic products.
A variety of GaN transistors are known and they include P-Channel transistors in conjunction with N-Channel transistors using an analog alloy to improve conductivity. The use of a tertiary alloy such as AlGaN (Aluminum-Gallium-Nitride) is often referred to as analog alloy in the art. To increase power handling capacity of GaN transistors, several techniques have been exploited to increase channel conductivity.
It is important to achieve low channel resistance so that the total power consumption can be reduced as well as the device speed can be improved. Increasing the carrier density is one common option that is exploited often. This can be achieved by using high Aluminum (Al) compositions such as AlGaN as back barrier beneath the GaN channel. Higher the aluminum content, higher is the channel conductivity. However thick analog AlGaN with high Al content cannot be grown on GaN buffer due to the lattice mismatch. This is a fundamental limit of using analog AlGaN alloys as the back-barrier.
The proposed technology overcomes this limitation by proposing a new way to increase channel conductivity while managing the stress related to lattice mismatch.